Investigation ofLi6+Ni64fusion at near-barrier energies

Abstract

The total fusion (TF) excitation function for a $^{6}\mathrm{Li}$ projectile with a $^{64}\mathrm{Ni}$ target has been measured using the online characteristic $\ensuremath{\gamma}$ ray detection method at energies around the Coulomb barrier. The complete fusion (CF) excitation function for the system is subsequently estimated from the dominating neutron evaporation channels with the help of statistical model predictions. The CF cross sections exhibit a suppression of about $13%$ compared to the one-dimensional barrier penetration model (1DBPM) at above-barrier energies, but no suppression is observed for TF cross sections. The observation does corroborate the estimated suppression for $^{6}\mathrm{Li}$ on $^{59}\mathrm{Co}$ target, but does not corroborate the recently proposed universal suppression factor for the $^{6}\mathrm{Li}$ projectile. The result supports the conjecture of reduced suppression of CF cross sections with decreasing target mass. At energies below the barrier, both the TF and the CF cross sections are enhanced. The observed enhancement of the CF process can be explained by channel coupling (CC), but the enhancement in TF cross sections is significantly higher than the CC predictions.